Abstract. In this study, the cellulose crystals, prepared by acid hydrolysis of flax fiber, consisted of slender rods with lengths ranging from 100 to 500 nm and diameters ranging from 10 to 30 nm, respectively. After mixing the suspension of flax cellulose nanocrystals (FCNs) and plasticized starch (PS), the nanocomposite films were obtained by the casting method. The effects of FCNs loading on the morphology, thermal behaviour, mechanical properties and water sensitivity of the films were investigated by means of wide-angle X-ray diffraction, differential scanning calorimetry, tensile testing, and water absorption testing. Scanning electron microscopy photographs of the failure surfaces clearly demonstrated a homogeneous dispersion of FCNs within the PS matrix and strong interfacial adherence between matrix and fillers, which led to an increase of glass transition temperature ascribed to the starch molecular chains in the starch-rich phase. In particular, these nanocomposite films exhibited a significant increase in tensile strength and Young's modulus from 3.9 to 11.9 MPa and from 31.9 to 498.2 MPa, respectively, with increasing FCNs content from 0 to 30 wt%. Also, with a loading of FCNs, the resulting nanocomposite films showed a higher water resistance. Therefore, FCNs played an important role in improving the mechanical properties and water resistance of the starch-based materials.

Abstract

No abstract

No abstract

A detailed study of a novel synthesis via colloidal sol-gel route for obtaining nanoparticulate Nb 2 O 5 was performed. Parameters such as temperature and H + :Nb 5+ and Nb 5+ :H 2 O molar ratios were controlled in order to determine the best conditions of synthesis. Moreover, particle size distribution, zeta potential, structure by X-ray diffraction, and the photocatalytic activity of the particulate sols were also evaluated. The obtained results indicate that the colloidal sol-gel synthesis is a good alternative for obtaining Nb 2 O 5 either as stable nanoparticulate sol or as a nanosized powder. Nb 2 O 5 amorphous nanoparticles with an average size of 20 nm were obtained by controlling the synthesis variables. The heat-treatment process allowed the formation of Nb 2 O 5 with orthorhombic structure that transforms at higher temperatures to monoclinic phase. The highest photocatalytic activity was observed under k = 365 nm, the smallest UV energy used in the experimental tests.